The answer to your question is tech divers use one or the other or both even. But, chances are, you won't see a technical diver using a standard recreational computer unless it has been put into gauge mode. The algorithms rec computers use just aren't conducive to technical dives. Computers from shearwater, ostc, and liquivision (a few models) are developed for technical divers. They are programmed with both VPM and gradient factors, with the diver deciding how aggressive or conservative they want to be with their deco. I haven't used any of the tech computers (i dive with a bottom timer), so i can't comment on what else they are capable of doing besides deco, gas switches, and trimix capable. I'm sure someone will be along to explain more in depth. On top of the primary computer, a diver either has a back-up computer or a back-up bottom timer in case of failure. If you're using a bottom timer as a back-up, the diver has also cut various tables with bottom times, stops, gas switches, etc. If you're using only a bottom timer, then you've cut tables based on your planned dive, but also tables in case SHTF, and you've lost gas, encountered some problem and your bottom time is longer than planned, etc. There are various programs you can use to cut your own tables, but you really need to know what you're doing.
Whether a computer or bottom timer is used, there is a lot more planning that goes into a technical dive than a normal recreational dive. Things like bottom time, depth, gas, etc are planned for in advance, and divers tend to know what their stops are going to be beforehand.
I myself am just starting down the tech path at the moment (all my dives are in recreational depths, but some of them require deco and have just taken an accelerated deco course as well).